the modern distiller

VM / LM upgrade

VM / LM upgrade

Postby myles » Thu Dec 20, 2012 7:26 am

My VM has gone through several variations and has ended up similar to Minime's version.

The head is basically vapour tight (but not cleaned up yet) and uses an offset double coil with a central feed. Mine is mounted through a T as I use 1 branch as the air vent and the other as part of the heads trap.

standard VM_LM.jpg

My version is based on 1.4" and 2" tube and is destined to mounted over a 3" column. I am working on the boiler / reboiler at the moment, but have completed the joint between the head and the column.

It is a 2" compression tank connector, fitted and soldered into a 3" end cap, that will be soldered onto the column.

VM Head joint.jpg

Now I know some folks have issue with brass connectors, but in larger sizes these are easy to overcome, and besides I just like the look of copper and brass together. The 2" hole in the fitting is OK for inserting packing into the column. In this size it is easy enough to cover any vapour exposed brass with solder if you really want to.

Boiler to come. :smile:

The short stub of tube will be soldered into the bottom of the head.
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Re: VM / LM upgrade

Postby Rockchucker » Thu Dec 20, 2012 11:55 am

I so admire your work Myles!
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Re: VM / LM upgrade

Postby Kapea » Thu Dec 20, 2012 12:08 pm

One of the few subject bans I have seen (possibly the only one) on AD is the ban on posting about pickling brass. Pint was pretty firm in stating it is not allowed. (because it is not needed for brass to be safe)

With modern metallurgy, using brass in your still is no big ting bruddah.

I'm with you guys - shiny brass looks good with shiny copper!
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Re: VM / LM upgrade

Postby myles » Sat Dec 22, 2012 5:21 am

Well I had quite a productive day and finished off my water sealed boiler / thumper / re-boiler. It is a multi purpose alembic style pot that will be used as:

1. A vapour infusion pot still
2. The re-boiler to go under my VM column
3. As a thumper if I ever need another one.

I was slightly wrong with my estimate of capacity though. It is only 22 litres, not the 25 that I mentioned previously. However, 22 litres is ample for the intended uses.

water seal pot.jpg

I haven't fully polished this one as I am not sure yet if I am going to insulate it.
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Re: VM / LM upgrade

Postby myles » Thu Jan 03, 2013 12:47 pm

I finally managed to get enough time away from the festivities to complete the lower section of the column. I am a bit concerned about potential pressure in the column and the effectiveness of the water seal, so there has been a minor change. I have put a cone on the base of the column and the outer cap of the water seal. However, I decided to incorporate a mechanical seal also.

This is the plan:

water sealed 2.png

The cone will allow adjustment of the column to vertical. I soldered a 3mm copper wire to the inside of the inner collar to act as a support for a 7mm O ring. This is actually 7mm platinum cured silicon tube, fashioned into an O ring. Of course I rushed it :roll: and soldered the wire on flush with the top of the collar instead of a few mm down, but I shall fix that tomorrow.

The mechanical seal with the O ring, combined with the weight of the column should be sufficient, but the water seal is there as a backup and to provide a visual indication of an over pressure situation.

I don't think the liquid suspended in the column could generate sufficient boiler pressure to be an issue, however I have a backup plan. I can chop off the lower section of this column to use as a botanical basket, (less pressure than a full packed column) and use a triclamp joint onto a 30 litre keg as the reboiler for the column. I have a spare keg that I can modify into a reboiler, so it is not a big deal. I just wanted to try this way first. :smile:
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Re: VM / LM upgrade

Postby myles » Sun Jan 06, 2013 3:52 am

This is just a dry run to see if the equipment will fit into the still room.


It will be a bit tight but it should all fit in - when I have finished building it all.

Anyhow, onto the column.


This is now 59" of 3" copper tube which is fully packed. There is a 2" stainless scrubber plug at the base then 54" of pumice packing, topped off with 3" of stainless scrubbers. The pumice packing has been graded. There is an 8" layer of slightly larger 1/2" gravel over which is 45" of smaller (fitted through a 3/8" square mesh) pumice chips.

The vapour path is fully insulated through to the VM valve

column head.png

There are 2 valves in the reflux line. A ball valve to divert all the reflux to the base of the column, and a gate valve to bleed off the heads. I am thinking of returning all the reflux to the top of the column for stabilisation and heads removal, and then switching to returning it to the base of the column for the hearts phase.

That funny mark on the column below the valves is a thermo port. I screwed and soldered a 3/8" compression fitting into the column wall. I have built a sealed thermowell that will take a 4mm probe and this is secured in place with the compression fitting. If necessary I can remove the thermowell and use the compression fitting to insert a 6mm thermo probe directly into the column. I need to buy a new 2 channel digital thermometer and have not decided which model to get yet - hence the options. The top thermo port in the vapour path, is a standard 1/2" compression fitting.

It has been mentioned that there might be issues with vapour getting up the reflux return line so I put 2 compression joints into the vapour trap.

column reboiler.png

This will make it easier to change the depth of the vapour lock if this is required.

The product condenser is my 2 tube shotgun with concentric vapour paths - essentially a liebig inside another liebig, with the outer jacket being provided by the coil.

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Re: VM / LM upgrade

Postby myles » Sun Jan 06, 2013 9:32 am

Now minime I do not know if this idea works or not. This is derived from the vapour reflux paper posted by Mike Nixon, and one of the fundamental points that fell out of that discussion was the fact that a reflux column can work without a reflux condenser. The column will generate SOME reflux condensate within the packing regardless. It MIGHT be necessary to remove some of the insulation, or to retain a portion of the reflux returned to the top - I just don't know.

I can always disconnect the return path and revert to a conventional VM / LM rig, that's why I put in the compression fittings.

If it will work as advertised, once heads have been removed returning reflux to the base of the column will increase the vapour ABV at the base of the column and decrease the temperature. This should make it easier for the packing to do its work and also enable a faster output.

The way I look at it is this. 1 thump chamber / bubble ball - increases the ABV of the vapour and makes the column work better. 2 or 3 chambers might do even more. This reflux return method has the same end result.

PROVIDED there is sufficient liquid entrapped on the packing, then any increase in vapour ABV entering the column is a good thing. It is why I put a valve close to the top of the reflux return line. In the partially open position, some reflux will go to the top of the packing and some to the bottom. If this turns out to be necessary, a more sensitive control mechanism might be required.

The least I can do is to look at product rates during the hearts phase under 2 conditions. All reflux to the top, compared to all reflux to the bottom.

I don't have an overflow fitted at the moment as I do not expect my reboiler to ever fill. If I use a standard 50 litre boiler and condense the vapour to charge the reboiler, even by the end of the run the reboiler should not have reached capacity.

Essentially I will be stripping the 30% ABV boiler charge into the reboiler, and then using the boiler to heat by steam injection, a 60% to 70% charge in the reboiler to feed the column.

Re: VM / LM upgrade

Postby myles » Thu Feb 07, 2013 11:57 pm

I am having second thoughts about this as I have concerns about the pressure required to prevent vapour flowing up the reflux return line. I think it will be too much for the liquid seal on the copper pot. That will just be retained as my boiler for gin and other infusions.

I am going to revert to plan B. Chop the bottom few inches off the 3" column and convert that bit into a botanical basket, and put a 3" to 2" reducer on the bottom of the column and use the small keg instead. I will just add a vapour injector into the keg so that it can still fill the same function as a reboiler under the column. Triclamp to keg might be more appropriate for the packed column.

Re: VM / LM upgrade

Postby myles » Sun Feb 17, 2013 4:01 am

OK I feel happier now with plan B. I modified the 30 litre keg into a thumper by adding a vapour injector into the upper dome.

VM LM Upgrade2a.png

The 3/4" tube goes all the way to the bottom of the keg and has 8 of 1/4" holes drilled in the last 3/4" of length. 2 rows of 4 holes offset so there is 1 hole every 45 degrees (aprox) (That empty T sticking out on the reflux return line is not in the liquid / vapour path, it is split down the back so I could fit the reflux return line through it, and was just there in case I wished to add a short stub of tube as a support for something)

The entire vapour injector can be removed for cleaning as there are no depth stops on that type of fitting. And the entire column

VM LM upgrade2.png

From the triclamp there is a 3" void, then 3" of stainless scrubbers, then 35.5" of pumice to the thermo port, then another 16.5" of pumice topped with another 2" of stainless scrubbers. Total packed length of 52" of pumice with a stainless plug at each end. My interpretation of a boil ball and packed column. :lol:
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Re: VM / LM upgrade

Postby Brewsmith » Mon May 13, 2013 6:31 am

Myles, could you post some detail on the LM return pipe on the top of the column? I am putting together a similar design, and I am not quite sure how to cut the pipe to best form a vapor lock. I think I saw someone just cut the end at a 45 degree angle, but I can't find that thread anymore and wanted to double check before I soldered it in. Thanks!
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Re: VM / LM upgrade

Postby myles » Mon May 13, 2013 9:31 am

Here you go.

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Re: VM / LM upgrade

Postby Brewsmith » Mon May 13, 2013 2:09 pm

Great, thanks for the diagram. So I guess I'll just run a straight 1/2 pipe into the column and then put on a street elbow to turn it up 90 degrees. Any input as to whether I should solder the elbow on vs a simple friction fit?
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Re: VM / LM upgrade

Postby myles » Mon May 13, 2013 6:04 pm

Well I soldered mine but I suppose push fit would work also. There is plenty of room inside the 2" tube to solder on a 1/2" fitting. Height inside the 2" column sets the max depth in the reservoir so don't make it too long. Its not shown but on my actual head the internal elbow is inside packing.

The restricted bit of tube below the T is empty.

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